<!DOCTYPE html>
<html>
<head lang="en">
    <meta charset="UTF-8">
    <title></title>
    <style>
        h2{
            margin-bottom: 0;
        }
        h2+p{
            margin-top: 0;
        }
        p{
            margin: 0 0 1em;
            /*【1】默认的段落之间有1倍的font-size的距离*/
        }
    </style>
</head>
<body>
<h2>this is 2rd headline</h2>
<p>this is the pra an not only one</p>
<p>this is the pra an not only one</p>
<p>this is the pra an not only one</p>
<p>this is the pra an not only one</p>
</body>
</html>